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Violent Engine Shaking

9K views 14 replies 9 participants last post by  Cosmicflash 
#1 ·
Today while i was passing a car on the highway my engine started to shake violently and acceleration gave out. Every time now when I hit the gas to accelerate the engine continues to shake violently. When the engine shakes acceleration kinda hangs and the car struggles to go faster. I can give it more gas making the engine shake even more and eventually the car will take off only to shake more again later. It feels like the belt is loose but i checked it and the belt location is fine and doesn't look loose. I contacted the Saab dealership and they said they couldn't get me in for 3 weeks! If you have any ideas on what is causing this or maybe how i can fix this my self that would be great. Thanks.
 
#3 ·
Bad Coil?

Sounds like a bad coil to me....not a lot of options but to take it to a dealer or an indie and check what codes its throwing. If my memory serves me correct, it wont throw a specific code for what cylinder isnt firing correctly, but they can figure it out by checking the coils. Thats where I would start. When was the last time the plugs were changed?


Drew
 
#4 ·
Im not sure when the plugs were last changed but I have 76,650 miles on the car and I think im due for a tune up. If it is a coil problem about how much would I be spending? I just ordered some new wheels and tires dropping $900 and will prolly have to cancel that order...talk about great timing for an engine failure.
 
#5 · (Edited)
Not sure what a coil would cost to replace. First start with your plugs, if the problem persists it shouldnt be as strong. But if it does persist, it could be a coil. From what youve said, it sounds like not all cylinders are firing....Hope this helps and check www.partsforsaabs.com for a coil. I will check right now....

Nothing available for our model years, dealer is probally your only option...sorry my friend...best of luck, let us know what happens.

Drew
 
#6 ·
I vote for a cylinder not firing too. I have a 99 VW Passat with the 1.8T and about a year ago it had similar symtoms. It was a bad ignition module that would frequently not fire the 3rd or 4th cylinder. With one jug not firing it can cause a tremendous shake!

I"m guessing that the CEL came on?
 
#7 ·
Talk to the folks at genuinesaab.com They should be able to give you some ideas on what to look at. They're a dealer, so they should be able to hook you up with a coil if necessary. The question would be how to you identify which one is bad.

Where abouts in Michigan are you? (I'm in Livonia)
 
#9 ·
What kind of violent shaking is it? side to side, or just an engine shake? if its just from the engine bay, just do the spark plug/coil/injector and air piping check first.

If its major whole car shaking violently type, you might have a driveshaft issue... but this is very unlikely.
 
#11 ·
Thanks for all the help and info. Oh i live in Kalamazoo MI and the closest Saab dealer is about a good hour's drive away in Grand Rapids. As for how the engine does idling its kinda weird. When in park or neutral the engine idols fine but as soon as I shift into drive and let it sit with the break applied it idols fine for a little bit then shaking occurs but not nearly as bad as when i'm accelerating. Also the dealer has me waiting for 3 weeks...i cant imagine this being a good thing driving it around. Thanks again for all your help
 
#12 ·
It's a vacume leak. You're last post confirms that - it's fine untill you use the brakes, which reduces vacume in the system, then it runs rough. Could be that the fuel pressure regulator is not getting enough vacume to operate correctly or somethign along those lines.

Tracking down a vacume leak is not rocket science. Any competent mechanic should be able to do it. You might call around to some of the larger shops around and see if someone has a fogging machine - Essentially, they plug the exhaust and pump a fog through the intake and look for where it's leaking...
 
#13 ·
A common site for vacuum leaks in these cars is the purge line for the charcoal cannister. It tends to crack where it enters the intake manifold right next to the dipstick tube.

Symptoms of a vac leak tend to manifest mostly at low rpms. The car may idle horribly. The brake assist only uses vacuum as pedal force is being applied. Once the brake pedal stops moving, the valving closes off vacuum to the booster.

Statistically vac leak is more common in this car than coil failure, bad plugs, etc. Unfortunately, a vac leak can throw error codes leading to unnecessary replacement of more expensive parts.

Check the purge line.
 
#15 ·
Socomv2285 said:
Thanks for all the help and info. Oh i live in Kalamazoo MI and the closest Saab dealer is about a good hour's drive away in Grand Rapids. As for how the engine does idling its kinda weird. When in park or neutral the engine idols fine but as soon as I shift into drive and let it sit with the break applied it idols fine for a little bit then shaking occurs but not nearly as bad as when i'm accelerating. Also the dealer has me waiting for 3 weeks...i cant imagine this being a good thing driving it around. Thanks again for all your help
Waiting 3 week is ridiculous!!

If you're up for it, drive a little further towards Chicago. Flikkema Saab is in Merriville, IN and Lansing IL. Less than a 2 hour drive. Most dealers in the Chicago area will take you immediately without an appt. This garbage of waiting for an appt. is unbelievable:nono;
 
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